1. Field
The present invention relates to a display device using a light source board, and manufacturing method thereof.
2. Description of the Related Art
Generally, a display device, for example a display device using liquid crystal, includes a light guide plate arranged on a surface opposite to a liquid crystal panel display surface and a light source such as a light emitting diode (LED) arranged on a side surface of the light guide plate. By propagating light from the light source in the light guide plate and diffusing the light in a diffusion pattern provided in the light guide plate, the light is extracted onto the display surface.
The display device further includes a middle frame for supporting a light guide plate arranged therein, a rear frame for supporting horizontal movement of the light guide plate arranged on a surface of the light guide plate which is opposite to the surface where a display panel is arranged, and a front frame for supporting the display frame and the middle frame and including an opening on the display surface of the display panel.
In assembling the display device, for example, there are processes as follows: reversing the middle frame; arranging a light source board with a light source arranged thereon, a light guide plate and a reflective sheet, by using a position regulating structure formed on the rear surface of the middle frame; fixing these components with a rear frame; and reversing the middle frame, light source board, light guide plate, reflective sheet and rear frame as an integrated components. The processes further includes: arranging an optical sheet by using a position regulating structure formed on the front surface of the middle frame; and fixing the optical sheet to the middle frame with an adhesive sheet. Then, the processes further includes: arranging a display panel by using a position regulating structure formed on the middle frame; and bending and caulking, or fixing with screws, fixing claws formed in plural positions of the outer edge of the front frame to the claw receiving portions formed on the circumference of the rear frame, thereby fixing and assembling the front frame and the rear frame.
In a display device disclosed in JP-A-2003-279934, an upper frame has a hole and a first protruding portion of a middle frame is fitted into the hole. A second protruding portion on the opposite side of the middle frame in the same position as the first protruding portion is fitted into a hole in a lower frame thus fixing the lower frame and the upper frame. As another example, a bent portion of a lower frame provided for positioning of a light guide plate is fitted into a hole in a middle frame to fix the bent portion thus preventing possible deformation of the bend portion.
In a display device disclosed in JP-A-2000-258756, a panel guide rib is provided on a resin frame thus supporting a liquid crystal panel.
In the above display devices, it is necessary to provide a plurality of position regulating structures on a middle frame. This complicates the structure and results in a larger frame area of a display device. A process is required to reverse a display device (reversing the front/rear surface of a display device) in assembly, which has raised a problem of an additional manufacturing process. In JP-A-2003-279934, a protruding portion formed on a middle frame must be formed on a rear frame and a front frame. This leads to a complicated structure and adds to the thickness of a display unit. Further, the protruding portion formed on a rear frame is intended to fix a light guide plate. However, there is no disclosure or teaching regarding the position regulation of a display panel. In JP-A-2000-258756, the protruding portion provided on a middle frame is intended to regulate the position of a display panel; therefore, it is necessary to provide a structure for regulating a reflective sheet, a light guide plate and an optical sheet. Another problem is that a position regulating structure of an optical sheet or a reflective sheet can be as thick as that of the optical or reflective sheet. This results in a lower position regulating capability and involves difficulty in the assembly work and displacement of the optical or reflective sheet caused by vibration or impact even after a display device is assembled.